Averaging device for measuring



Dec. 21, 1943. P. G. HoLT AVERAGING DEVICE FOR MEASURING VINSTRUMENTS Filed Nov. 18, 1942 Patented Dec. 21, 1943 UNITED STATES PATENT OFFICE AVERAGING DEVICE FOR MEASURING IN STBUMENTS (Granted under the act of March 3,- 1883, as amended April 30, 1928; 370 0. G. '157 11 Claims.

My invention relates in general to averaging devices, and in particular to a device for obtaining the average reading of a measuring instru-y ment over a predetermined period of time.

The particular object of my invention is to provide a device which will automatically take a predetermined number of separate readings of the measuring instrument and automatically totalize such readings to render an average value for such readings.

Another object is to provide means for obtaining the mid-time of the period over which the predetermined number of readings have been taken.

While the principles of my invention may be adapted to measuring instruments in general, it has particular value when applied to an octant or sextant or other equivalent angle measuring instrument utilized to measure the angle between a celestial body and the horizon.l

The following description accordingly concerns the application of my invention to this type of instrument, such instrument being wellv known in the art and having a pivotally mounted arm which is moved by an observer from a zero angle reference position tormeasure the angle between the celestial body and the horizon.

I am` aware .that averaging devices for this type of instrument are already known in the art, but it is believed that an averaging device made in accordance with the principles of my invention offers advantages not obtainable by any of the prior art structures.

For example an averaging device made in accordance with myy invention when applied to an instrument for measuring angles between-` a. celestial body and the horizon enables a complete set of observations to be made by one person alone. This desirablev result is obtained for the reason that no initial instrument reading needs to be taken of the angle between the celestial body and the horizon nor of the time when the angle averaging device is placed in operation.

.In the accompanying drawing, the single iigure of which clearly shows the essential features of my invention in diagrammatic form, the apparatus for taking the predetermined number of readings of the angle measured by a sextant arm I pivotally mounted on shaft II comprises a constant speed drive I2 of any suitable type, such as, for example, a spring loaded'escapement system (the details of which form no part of my invention and accordingly have been illustrated in block form only), which is adapted to rotate a shaft I3.

Shaft I3 is coupled by a clutch mechanism I4 consisting of clutching members I5 and Il to rotate a shaft I1 for a predeterminedvnumber of revolutions, each at a uniform time rate, as `will rotatable with shaft I1 meshes with a gear I S to rotate a stub shaft 20 suitably journalled. A. second clutch mechanism 2| consisting of clutching members 22 and 23 is provided for 'coupling shaft 20 with a second stub shaft 24 also suitably journalled and carrying a gear 25. Gear meshes with gear 26 which is secured on another suitably journalled stub shaft 21 which is preferably mounted co-axially with shaft II. An arm 28 is rigidly secured to shaft 21 and oscillates between a stop member 29 which is aligned with the zero reference angle position of the sextant arm I0 and a. lateral projection 30 carried by arm I0.

A third clutching mechanism 3I comprising clutch members 32 and 33 is provided forconnecting shaft 21 to a shaft 34, the latter having a pointer 35 rotatable over a dial 3B calibrated to give the measured angle.

Shaft 34 and a disc member 31 secured thereto are suitably journalled inbearings not illustrated and are fixed against axial movement. The left end of shaft 34 is reduced in diameter and provided with a keyed portion 38 which fits Within a key slotted portion 39 which is formed as part of the clutching member 32.

A cam 4I which rotates with shaft I1 is adapted to operate a cam follower 42, the latter being secured to one end of a lever 43 pivotally mounted at 44. The other end of lever 43 is adapted to ride in an annular groove 45 which is formed as part of clutch member 23. Lever 43 is biased by spring 46 to disengage clutch member'22 from clutch member 23 of clutch mechanism 2i when cam follower 42 occupies rthe position shown in the drawing.

Another cam 41 is provided to rotate with shaft I1 and this cam is adapted to operate a a lever 49 which is pivotally mounted at'50.

The other enlarged end of lever 49 is adapted to ride in an annular recess 5I which is formed as a part of clutch member 32, and a spring 52 is provided to maintain clutching members 32 and 33 of the clutch mechanism 3| in a disengaged position when cam 41 is in the position shown on the drawing.

As will be evident from the -drawing, -when cam 4I rotates with shaft I1 cam follower 42 will be moved to the left, effecting counterclockwise motion of lever 43 and thereby causing clutch member 23 to become engaged with clutch member 22. A cantilever spring 53 may be provided to urgev clutch member 23 into engagement with clutch member 22 as lever 43 is so rotated.

In a similar manner as cam 41 rotates with shaft I1, cam follower 4l will move to the right, effecting clockwise motion of lever 4! and-hence hereinafter be explained in detail. A. gear I4 40 operate to effect engagement between clutch members 32 and 33 of clutch mechanism 3|.

` Another cantilever spring 5d may be provided to urge clutch member 32 into engagementwith clutch member 33 when lever Q9 is' so rotated.

The timing mechanism referred to above consists of a push buttoi 55 secured to a rod member 56 having a notched portion 57. Rod 56 is pivotally connected at 38 to a lever 59 which j is pivotally mounted at Gil, and a spring Si may be provided to urge lever 59 for counterclockwise rotation. The lower enlarged end of.

the pivoted lever 59 rides in a recess t2 which may be formed as a part of clutch member it.

As push button 55 is moved to the right, such action will effect clockwise rotation of lever 59 and cause clutch member i6 to become engaged with clutch member i5. This clutching action couples shaft i7 to shaft i3, the latter being driven by the motor mechanism H2, as previously explained. A gear 53 rotating with shaft i7 is adapted to rotate a gear tti through an idler gear t5, the gear @fl being mounted on a stub shaft t@ suitably journalled. y

A timing disc-,t7 rotatable with shaft 6E is provided for maintaining clutch members i5 and le of the clutch mechanism iii in engagement with each other for a predetermined length of time, such time being the time necessary for the disc S7 to make One complete revolution. This is achieved by providing a raised portion 63 at one point on disc t7. When the raised portion @t occupies the position shown in the drawing, a lever t9, which is pivotally mounted at 7K7, is raised against an opposed biasing action furnished by a spring 7l. Lever t9 carries a pawl 72 at its free end and this pawl is'adapted to t within notch 57 provided in rod 5G. As the time cycle is started by moving push button 55 and rod 5@ to the right, pawl 72 rides along the surface of rod 53 and when it reaches notch 57 pawl 72 will move down into the notch Fe7 under the infiuence of spring member 7i' locking in clutch members l5 and lf3 and starting rotation of shaft i7. However. when disc S7 completes one revolution, the raised portion td thereon will operate to move lever 69 upwardly and hence clisengage pawl 72 from notch 57, `which allows spring Cil to pull lever d@ in a counterclockwise direction and disengage clutch member i6 from clutch member i5 to stop shaft To automatically record the mid-time of the predetermined period that shafts i3 and i7 are coupled together. another disc 73 is provided which rotates with shaft S6. Disc 73 is similar to disc $7 and includes a raised portion 7d which isfdisposed 180 out of phase with the raised portion E8 on disc 57.

A lever 75 pivoted at 76 and biased in a counterclockwise sense lof rotation by spring 77 is provided and functions when lever 75 is rotated clockwise b v the raised portion 75 of disc 73 to automatically stop a watch 78 which may be suitably supported in a frame member not illustrated. Since the timing mechanism will function for one complete revolution of the disc will be stopped at the midpoint of the time for which the timing mechanism operates.

v Operation My device operates in the following manner: The sextant is raised to sighting position by spring 52 the observer and the observer then rotates the sextantarm lll which adjusts the optical system in the sextant until the celestial body has been brought into coincidence with the horizon. He then starts the motor mechanism i2 and shaft I3 to rotate and presses upon push button 55 which functions to cause clutch members i5 and i6 of clutch mechanism lli to become engaged and locked in engagement through theA latching mechanism provided by the notch portion 57 and pawl 72.

Shaft i7 will then begin to turn at a fixed time rate per revolution, rotating gears 63, i3 and i9, and cams tl and t7, as previously described. Cam t7 is set somewhat in advance of cam di so that as cam t7 rotates, cam follower il@ will move to the right and eect engagement between clutch members 33 and 32 of clutch mechanism 3l, as previously described. Such action will cause shaft 315 and hence pointer 35 to rotate with rotation of gear 26, the latter being set into rotation shortly after clutch mechanism 3i has been actuated through operation of the cam follower Q2 on cam il which initiates rotation of gear through the clutch mechanism 2l, as previously explained. y

Arm 28 being secured rigidly to shaft 27accordingly rotates in step with pointer until the former strikes against the laterally extending projection 3b carried by the arm it. Since arm 28 and gear 26 are secured rigidly to shaft 27, gear 2S will also be stopped when arm 223 is stopped, thereby stopping rotation of gear 25 and causing the driven clutch member 22 to slip with respect to the driving clutch member 23 for so 'long a time as the cam follower G2 remains upon the high portion of c arn di.

As cam follower l2 moves downwardly off the high portion of cam lil, spring d6 will now function to move clutch member 23 out of engagement with clutch member 22. Likewise, when cam follower i8 ride's down from the high portion of cam 7, clutch members 32 and 33will become disengaged by thebiasing action of the Gears 25 and 26 are then free to rotate and a torsion spring 79 functions to rotate the arm 28 back against its stop member 29.

This order of events' is repeated for each. revolution of shaft i7 and cams di and di and thereby causes pointer 35 to be moved step by l step with each oscillation of lever 28.

To hold pointer 35 in the position to which it is moved upon each revolution of cams lli and t7, a friction disc 80 is loosely mounted on shaft 36 and this disc is maintained in frictional engagement with an end face of disc 31 at all times by means of a lever 3| pivotally mounted at B2.

Y One end of lever 8l is provided with a protuberance 83 which fits within a complementary recess 84 in the disc 80, a cantilever spring 85 being provided to urge disc into frictional engagement with y disc 31. Thus when clutch members 32 and 33 are engaged, the disc 31 and pointer 35 are turned against the opposing friction furnished by disc 80 but when clutch members 32 and 33 are disengaged, the disc 31 and.

clutch members l5 and I6, thereby stopping the shaftv I7..

In order that-the pointer 35 may read the assaoss average of all of the predetermined number of measurements made by the arm 2l, the dial I6 is so calibrated that the angle measured by each stepped movement of the pointer 35 is equal to the reciprocal of the predetermined number of measurements whichare made. In other words, for example, if the timing mechanism is so set that shaft I1 and cams 4| and `"will make ilfteen complete revolutions, which meansvthat arm 28 will move fifteen times between its stop member 2l and the projection 30 carried by sextant arm Il, then dial 36 will be so calibrated that pointer II will indicate thereon only oneilfteenth of any angle measured by arm 28.

All during the operation of the timing mechanism, the observer, ot course, will move sextant arm il continuously with the relative movement between the celestial body and horizon so as to keep the celestial body and the horizon in coincidence. Thus, when the timing mechanism has rungts course, the observer may look upon the dial l. and read oi! the average value of the angles measured and may also obtain from the watch 18, the mid-time of the period during which the predetermined number of measurements were made by the mechanism.

To reset the pointer to a zero angle position on dial Il, any suitable mechanism such as a cardiod cam Il ilxed to shaft 34 and a cam plunger 8l may be utilized. The cam plunger Il may be provided with a cam surface Il which rides upon and turns lever 8l in a clockwise f rotation to release friction disc 8l from disc 31 during the resetting operation.

In conclusion, it will be evident that I have provided an averaging device which is a decided advance in the art and which does not require any initial reading to be taken of the angle between the celtial body and the horizon or the time when the angle averaging device is placed i operation.

It will also be evident that the present embodiment is illustrative of only one form of the invention and that many changes may be made without departing from the sc'ope of the invention as defined in the appended claims.

'I'he invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon o r therefor.

Having thus set forth and disclosed the nature of this invention, what is claimed is:

l. In a device for averaging a plurality of measurements of an instrument over a predev termines period of time, sind instrument having means' displaceable in accordance with each said measurements of the instrument, the combination comprising measuring means operable over said period of time and controlled as to degree of movement by said displaceable means for automatically taking a predetermined number of uniformlytime spaced measurements of said intion comprising timing means, measuring means controlled as to degree of movement by said displaceable vmeans and including said timing means for automatically taking a predetermined number of uniformly time spaced measurements of said instrument displaceable means over said period of time, totalizer means operable progresslvely by and in accordance with each operation of said measuring means for totalizing said measurements, said totalizer means being calibrated to indicate a single average measurement of said instrument displaceable means over said period of time, and means operable by said timing means to register the time at the midpoint of said period of time.

3. In a device for averaging a plurality of measn urements of an instrument over a predetermined period of time, said instrument having means displaceable in accordance with each said measurement of the instrument, the combination comprising an oscillatory member, means for automatically obtaining a predetermined number of oscillations of said oscillatory member between a stop position and the displaceable means of said instrument, a totalizer carried by said de? vice for averaging said plurality of instrument measurements, and vmeans coupling said totalizer to and for operation step by step with each oscillation of said oscillatory member, said totalizer being calibrated to indicate a single average measurement of said instrument upon the completion of the predetermined number of step by step movements thereof.

4. In a device such as a sextant for' obtaining the mean altitude of a celestial body over a period of time, said sextant including means adapted to be continuously adjusted during said time period for continuously measuring the angle between said celestial body and the horizon, the combination comprising measuring means controlled as to degree of movement by said adjusted means for automatically taking a predetermined number of uniformly time spaced measurements of the angle measured by said sextant adjusting means, and angle totalizer means operable progressively by and in accordance with each such operation of said measuring means, said totalizer means being calibratedto indicate a single average measurement of all of said angles measured.

5. In a device such as a sextant for obtaining the mean altitude of a celestial body over a period of time, said sextant including means adapted to be continuously adjusted during said time trolled as to degree of movement by said adjusted strument displaceable means, and totalizer means,

operable progressively by and in accordance with each operation of saidv measuring means for totalising said measurements, said totalizer means being calibrated to indicate a single average measurementof said instrument displaceable means over said period of time.

3. In a device for averaging a plurality of measurements'oL-an instrument over a predeterminednperiod of time. said instrument having means displaceable in accordance with each said measurement of the instrument, the combinameans for automatically taking a predetermined number of uniformly time spaced measurements of the angle measured by sextant adjusting means, angle totalizer means operable progressively by and in accordance with each such operation of said measuring means, said totalizer means being 'calibrated to indicate assingle average measurement of all of said angles measured, and means operable to register the time when onehalf of the predtermined number of measurements of said angle have been taken.

6. In a device such as the mean altitude of a celestial body over a period of time, said sextant including means adapted to be continuously adjusted during said time period for continuously measuring the angle between said celestial body and the horizon. the

a sextant for obtaining t combinatiorn comprising a drive shaft, means including constant speed motor means and timing means for rotating said drive shaft a predetermined number of revolutions at a fixed time rate per revolution, a driven shaft, a lever mounted on and rotatable with said driven shaft, means for coupling said driven shaft to said drive shaft to oscillate saidA lever once between a stop position therefor and said sextant adjusting means for each revolution of said drive shaft, angle totalizer means, and means coupling said totalizer means to and for operation step by step with each oscillation of said lever, said totalizer means being calibrated to Vindicate a single average measurement of said sextant upon the completion of the predetermined number of step by step movements thereof.

7. The combination 'in claim 6 and including means operable by said timing means for registering the time when one-half of the predetermined number of revolutions of said drive shaft have been completed.

8. In a device such as a sextant for obtaining the mean altitude of a celestial body over a period of time, said sextant including an angle measuring arm adapted to be moved continuously during said time period for continuously measuring the angle between said celestial body and the horizon, the combination comprising a drive shaft; means, including constant speed motor means and timing means for rotating said Idrive shaft a predetermined number of revolutions at a xed time rate per revolution, a driven shaft, a lever mounted on and rotatable with said driven shaft, neans for coupling said driven shaft to said drive shaft to oscillate said lever once be-I tween a stop position therefor and said sextant arm for each revolution of said drive shaft, angle totalizer means, and means coupling said totalizer means to and for operation step by step with each oscillation of said lever, said totalizer means being calibrated to indicate a single average measurement of said sextant upon the completion of the predetermined number of step by step movements thereof.

` termined number of revolutions, a driven shaft,-

tering the time when one-half the predetermined number of revolutions of said drive shaft have been made.

10. In a device such as a sextant for obtaining the mean altitude of a celestial body over a period of time, said sextant including an angle measuring arm adapted to be moved continuously during said time period for continuously measuring the angle between said celestial body and the horizon,

the combination comprising a drive shaft, constant speed motor means, first clutch means for coupling said motor means to rotate said drive shaft at a fixed time rateeper revolution, timing means operable to disengage said first clutch means upon completion of a predetermined number of revolutions of said driven shaft, a driven shaft, a lever mounted upon and rotatable with said driven shaft, a iirst 'cam rotatable with said drive shaft, means including a follower for said rst cam and clutch means for coupling said driven shaft with said drive shaft to oscillate said leveronce between a stop position therefor and said sextant arm for each revolution of said drive shaft, angle totalizer means including a scale and a pointer operable over said scale, the latter being so calibrated that said pointer in moving thereover will indicate for each oscillation of said lever actual angular movement of said lever divided by the number of oscillations thereof, a second cam rotatable with said drive shaft, and means including a follower for said second cam and clutch means for coupling said pointer to be moved progressively with each oscillation of said lever.

l1. In a device such as a sextant for obtaining the mean altitude of a celestial body over a period of time, said sextant including an angle measuring arm adapted to be moved continuously during said time period for continuously measuring the angle between said celestial body and the horizon, the combination comprising a drive shaft, constant speed motor means, first clutch means for coupling said motor means to rotate said drive shaft at a fixed time rate per1 revolution, timing means operable to disengage said first clutch means upon completion of a predea lever mounted on and rotated by said driven shaft, a first cam rotated by said drive shaft,

means including a, follower for said first cam and clutch means operated by said followers for coupling said driven shaft with said drive shaft to tating said drive shaft a predetermined number v of revolutions at a fixed time rate per revolution, a driven shaft, a lever mounted on and rotatable with said driven shaft, a first cam rotatable With said drive shaft, means including a follower for said first cam and clutch means for coupling said driven shaft with said drive shaft to oscillate said lever once between a stop position therefor and said sextant arm for each revolution of said drive shaft, angle totalizer meanssaid totalizer means comprising a scale and a pointer operatively connected to rotate progressively with each oscillation of said lever` over said scale, said scale being so calibrated that said pointer in moving thereover will indicate for each oscillation of said oscillate said lever once between a stop position therefor and said sexta-nt arm for each revolution of said drive shaft, angle distance totalizer means including a pointer operated by said driven shaft to move over a scale so calibrated that said pointer in moving thereover will indicate for each oscillation of said lever actual angular movement of said lever divided by the number of oscillations thereof, a second cam rotated by ysaid drive shaft, means including a second follower for said second -cam and clutch means operated by said second follower' for coupling said pointer to be rotated step by step with each oscillation of said lever, and means operable by said timing means for registering the time when one-half the predetermined number of revolutions of said drive shaft-have been made.

, PLINY G. HOLT. 

